The Pros + Cons Of Intermittent Fasting, According To A Functional Medicine Expert

The Pros + Cons Of Intermittent Fasting, According To A Functional Medicine Expert Dr. Will Cole

In my telehealth functional medicine clinic, there are certain tools I use alongside diet and supplements to help people reach their health goals. One of my favorites is intermittent fasting. This practice has been used for years but has recently become more popular in the wellness world as more research has been done to show its benefits.

With that being said, fasting isn’t a one-size-fits all tool for everyone in all situations. There are pros and cons to intermittent fasting that you need to be aware of before jumping head first into a fasting practice. So how do you know if intermittent fasting is right for you? Let’s take a look at what fasting is, the different ways you can fast, and what you need to know about the pros and cons of intermittent fasting in order to use this tool to elevate your health.


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What is intermittent fasting?

Intermittent fasting is a tool that has received a lot of buzz in the wellness world but it can be a little confusing if you are new to the concept. Simply put, intermittent fasting is when you go without eating food for an extended period of time as a way to lower inflammation and achieve certain health benefits.

Once your fasting window is over with, you will break your fast with food and eat all of your calories for the day during that time frame before your fasting window starts again. The amount of time that you fast for can vary depending on your health case. Ideally, you would start off with shorter fasting windows and gradually increase the time between meals as your body adjusts.

Here are a few examples of fasting windows that you can follow:

  • The 8-6 window plan

In this plan, you can eat anytime between the hours of 8a.m. and 6p.m. Once 6:00 hits, you stop eating for the next 14 hours until 8:00 the next morning.

  • The 12-6 window plan

Building off of the previous plan, you will eat between the hours of 12pm and 6pm. You’ll still stop eating at 6pm but you’ll extend your fasting time an extra 4 hours until 12pm the next day.

  • The modified 2-day plan

This plan is a little bit different from your traditional fasting plan. Instead, you will eat a clean diet 5 days of the week and the other two days your diet will consist of clean foods equalling 700 calories total.

  • The every other day plan

This plan is exactly as it sounds, you’ll eat clean one day and fast for all day the next.

  • OMAD

OMAD stands for one meal a day. In this plan, you’ll fast for 23 hours before breaking your fast and eating all your food for the day in one hour. Typically, people will break their fast for dinner but you can break your fast at any time of the day whether that is breakfast or lunch.

Whatever plan you decide to follow, here are a few things to note when it comes to the food that you do eat. Intermittent fasting isn’t an excuse to eat whatever you want. It’s important to still eat clean, whole food sources like healthy fats, clean meats, vegetables, and some fruit. You can also have herbal tea and a little bit of coffee and tea. After all, you won’t want to negate the health benefits of fasting with sugary, processed foods.

What are the benefits of intermittent fasting?

The pros and cons of intermittent fasting are varied, but the pros certainly take center stage. These are some of my favorite ways intermittent fasting targets different areas of your health to restore your body from the inside out.

1. It restores your gut health

Your microbiome is not stagnant. In fact, the bacterial colonies of your gut ebb and flow throughout the day, rising and falling based on if you are sleeping, eating, or awake. While this is normal, our traditional 3 meals a day schedule plus snacking isn’t. This constant eating throws off this natural rhythm but giving your gut a break from eating can restore it to its natural flow. 

Studies also show that fasting lowers inflammation in gut problems like IBS and Crohn’s disease while also lowering inflammatory markers IL-6 and CRP.

2. It boosts your immune system

Since the majority of your immune system - close to 70%! - is located in your gut, it makes sense that rehabbing your gut health with fasting can also boost your immunity. Research has shown that fasting can upregulate (1) proteins that support your immune systems while also lowering white blood cell count to induce (2) the production of new white blood cells. This is especially important considering they are the main defense mechanisms of your immune system for invading pathogens. Fasting can also prompt your body to reuse immune cells that are no longer needed.

3. It curbs your cravings

You may think that you’ll be starving when you fast, but that couldn’t be further from the truth! It may take a little adjustment but as you continue intermittent fasting, your hunger hormone ghrelin decreases resulting in fewer cravings. Plus, fasting helps you switch your metabolism from burning sugar to burning fat which helps you stay satiated longer after each meal.

4. It improves your brain function

Mental health problems like anxiety, depression, and brain fog are on the rise, and studies are showing that IF improves (3) brain function and mood through an effect not unlike antidepressant medication. Even neurological conditions like Alzheimer’s and Parkinson’s seem to respond positively to IF, and several studies have shown (4) that IF may actually protect neurons from genetic and epigenetic stress factors, meaning it can essentially slow down brain aging.

5. It recharges your metabolism

As I talk about in my book Intuitive Fasting, our modern eating schedule and how often we eat doesn’t always reflect our bodies’ natural eating schedule. It can actually lead to metabolic inflexibility which can cause weight gain, fatigue, inflammation, and other health problems. Intermittent fasting on the other hand, has been the default of our ancestors with our bodies functioning best with times of fasting. Intermittent fasting resets your metabolism to switch more efficiently between burger sugar and fat for fuel and restores your energy, inflammation levels, and overall health in the process.

6. It improves cellular health

The 37.2 trillion cells in your body make up your organs, bones, and muscles and play a role in how your body functions. Basically, if your cells aren’t healthy, you won’t be either. One way your body keeps your cells healthy is through a process called autophagy. Autophagy is a cellular recycling process that helps break down damaged cells and recycle them out of your system. Studies have shown that intermittent fasting can enhance (5) autophagy to significantly renew your cellular health.

7. It can heal your relationship with food

At first glance, fasting can seem extremely restrictive and the opposite of food freedom. However, if done with the right intentions you’ll be able to take back control of your hunger. By getting in touch with your instinctive eating patterns, you’ll become healthier and more mindful about how and when you eat. When your body is out of balance it can be very difficult to discern what it needs to build vibrant wellness.

What are the risks of intermittent fasting?

Although fasting has many benefits, it might not be right for everyone in all situations. Now that’s not to say you can’t fast, but you may have to be more mindful with how you fast if you fall into any of the following categories.

1. You have a history of eating disorders

While fasting can help you become more intuitive about eating and your relationship with food, if you have a history of eating disorders fasting may be triggering for you. Always be aware of how you are feeling mentally when you start fasting, give yourself grace, and allow yourself to make adjustments if you feel like you are falling back into old patterns.

2. You have blood sugar problems

When patients come in with blood sugar problems I like to recommend IF due to its proven ability to increase (6) metabolism and lower insulin resistance. (7) If you have a blood sugar problem and want to try fasting it’s key to work with your doctor who can monitor you and slowly increase your length of fasting as your glucose stabilizes.

3. You are a woman

When it comes to intermittent fasting, women are usually more sensitive than men. This is due to the fact that women have more kisspeptin, which creates greater sensitivity to fasting. If not done properly, IF can cause an irregular cycle and throw off their hormones. While more research needs to be done, it would make sense to logically conclude that this hormonal shift could affect metabolism and fertility too.

4. You are super active

It is completely possible to have a successful intermittent fasting practice while being super active however, you do need to be mindful about the amount of calories that you are consuming. The more active you are the more calories you need to thrive, so be aware that you may have to make adjustments according to your activity level.

Consulting a functional medicine professional

Now that you know the pros and cons of intermittent fasting, you can make an informed decision on whether or not intermittent fasting is right for you. If you do decide that you would like to incorporate fasting into your wellness routine but don’t know where to start my book, Intuitive Fasting walks you through a 4-week intermittent fasting plan complete with meal plans and recipes.

If you have been intermittent fasting for a while or have hit a plateau it may be time to work with a functional medicine practitioner. In my telehealth functional medicine clinic, we work with people all over the world on overcoming their underlying health problems by putting together healing plans that work for your specific biochemistry. We take bioindividuality very seriously, and that goes hand-in-hand with helping you find a fasting practice that works for you - or not if it isn’t relevant for your health.

Ultimately, fasting can be a great tool for healing but always consider the pros and cons in light of your unique health case.

As one of the first functional medicine telehealth clinics in the world, we provide webcam health consultations for people around the globe.


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  1. Ayse L. Mindikoglu, Mustafa M. Abdulsada, Antrix Jain, Jong Min Choi, Prasun K. Jalal, Sridevi Devaraj, Melissa P. Mezzari, Joseph F. Petrosino, Antone R. Opekun, Sung Yun Jung “Intermittent fasting from dawn to sunset for 30 consecutive days is associated with anticancer proteomic signature and upregulates key regulatory proteins of glucose and lipid metabolism, circadian clock, DNA repair, cytoskeleton remodeling, immune system and cognitive function in healthy subjects” Journal of Proteomics, Volume 217, 2020, 103645, ISSN 1874-3919.
  2. Cheng, Chia-Wei, Adams B. Gregor, et. al. “Prolonged Fasting Reduces IGF-1/PKA to Promote Hematopoietic-Stem-Cell-Based Regeneration and Reverse Immunosuppression” Cell Stem Cell 2014. VOLUME 14, ISSUE 6, P810-823 DOI:
  3. Hussin, N M et al. “Efficacy of fasting and calorie restriction (FCR) on mood and depression among ageing men.” The journal of nutrition, health & aging vol. 17,8 (2013): 674-80. doi:10.1007/s12603-013-0344-9
  4. Martin, Bronwen et al. “Caloric restriction and intermittent fasting: two potential diets for successful brain aging.” Ageing research reviews vol. 5,3 (2006): 332-53. doi:10.1016/j.arr.2006.04.002
  5. Jamshed, Humaira et al. “Early Time-Restricted Feeding Improves 24-Hour Glucose Levels and Affects Markers of the Circadian Clock, Aging, and Autophagy in Humans.” Nutrients vol. 11,6 1234. 30 May. 2019, doi:10.3390/nu11061234
  6. Aly, Salah Mesalhy. “Role of intermittent fasting on improving health and reducing diseases.” International journal of health sciences vol. 8,3 (2014): V-VI. doi:10.12816/0023985
  7. Harvie, Michelle et al. “The effect of intermittent energy and carbohydrate restriction v. daily energy restriction on weight loss and metabolic disease risk markers in overweight women.” The British journal of nutrition vol. 110,8 (2013): 1534-47. doi:10.1017/S0007114513000792

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Dr. Will Cole, DNM, IFMCP, DC is a leading functional medicine expert who consults people around the globe, starting one of the first functional medicine telehealth centers in the world. Named one of the top 50 functional and integrative doctors in the nation, Dr. Will Cole provides a functional medicine approach for thyroid issues, autoimmune conditions, hormonal imbalances, digestive disorders, and brain problems. He is the host of the popular The Art Of Being Well podcast and the New York Times bestselling author of Intuitive Fasting, Ketotarian, The Inflammation Spectrum and the brand new book Gut Feelings: Healing the Shame-Fueled Relationship Between What You Eat and How You Feel.

Gut Feelings Dr. Will Cole 6

Gut Feelings

Healing The Shame-Fueled Relationship
Between What You Eat And How You Feel